Conventionally, in cataract surgery and other operations, a method has been adopted wherein a crystalline lens is extracted and removed from the capsule through an incision made on ocular tissues such as the cornea (sclera) and anterior lens capsule, and thereafter, an intraocular lens is inserted into the eye via the above incision to be set in the capsule in lieu of the removed lens.
In such operations using an intraocular lens, insertion tools for intraocular lenses such as those described in Patent Documents 1 and 2 are commonly used. In general, these insertion tools for intraocular lenses are used to place an intraocular lens within the lens capsule by means of inserting the tip opening of an insertion cylinder located at the tip of the tool body through an incision and pushing out the intraocular lens in a compactly deformed condition from the tip opening of the insertion cylinder, which unfolds out within the lens capsule with its own restoring force. Using this type of insertion tool allows us not only to minimize the incision and save time and effort for operations, but also to reduce the risk of post-operative astigmatism and infections.
Meanwhile, the intraocular lenses often have different shapes between their front and back sides such as those, for example, with the haptic tilting toward the front surface of the lens (cornea side) in order to suppress secondary cataract by pushing the optical zone against the rear interior (vitreous side) of the lens capsule. For this reason, the intraocular lens requires its front and back sides placed correctly in the capsule.
However, conventional insertion tools for intraocular lens had a problem that the front and back sides of the intraocular lens tend to be flipped within the capsule. Therefore, the operator needed to displace the insertion tool in the rotational direction by an amount that assumes a counterturn before inserting it into the eye in order to avoid difficult work of reversing the turn of the intraocular lens in the right direction within the capsule after the operation, or to turn the insertion tool as soon as the intraocular lens unfolds inside the capsule after being pushed out of the insertion tool. However, such a manipulation is not easy, requiring skilled hands. Especially, the operator was hard-pressed to work carefully not to cause any damage to the incision and the like in turning the insertion tool.    Patent Document 1: JP-A-2003-70829    Patent Document 2: JP-A-2004-351196